1. Field of the Invention
The present invention relates to an input device for inputting coordinates and a driving device thereof, more specifically, to an input device that vibrates an operational panel thereof in input operations, and a driving device thereof.
2. Description of the Related Art
When inputting data from a touch panel (or a touch pad) using a pen or fingers, because there is not feeling of operations, like clicking a mouse or pressing a key of a keyboard, the operator cannot clearly recognize if the panel or the pad is surely pressed with the pen or fingers and if data input is surely performed, and this causes errors in the input operation. In order for the operator to recognize the operation of pressing the touch panel or pad with the pen or fingers, it has been proposed to make the touch panel vibrate. The proposed devices are introduced below.
Japanese Patent Application Laid Open, No. 11-85400 (for example, FIG. 1) discloses a device for vibrating the touch panel by using a piezoelectric element. Japanese Utility Model Publication No. 3085481 (paragraph number 0037) discloses a device in which an actuator including coils and magnets is arranged below the touch pad of a portable personal computer. International Patent Publication WO00/078095 (from line 24 in page 38 to line 5 in page 42) discloses a planar acoustic conversion device in which the actuator for vibrating a plane includes a pair of magnets having opposite polarities and a pair of coils facing the magnets respectively. The pair of magnets and the pair of coils interact with each other magnetically, and thereby vibrate the object plane in a direction perpendicular to the plane.
In the device of the related art for vibrating the touch panel by using a piezoelectric element, because the vibration amplitude of the piezoelectric element is small, a multi-layer structure including multiple piezoelectric elements has to be used to obtain a large enough vibration amplitude. Consequently, the piezoelectric element becomes thick and expensive, and a high voltage is required to drive the piezoelectric element.
In the device of the related art in which an actuator including coils and magnets is arranged below the touch pad, it is difficult to make the device thin because of the existence of the actuator below the pad.
In the device of the related art in which the actuator for vibrating a plane includes a pair of magnets and a pair of coils, the magnets and the coils have to be arranged over the vibrating plane, and as a result, when applying this device to a touch panel in which the vibrating plane serves as a display screen, image displaying on the vibrating touch panel may be hampered.